﻿<topic>
	<head>
		<title>Constant Scan</title>
		<keywords>
			<keyword term="execution plan, constant scan"/>
			<keyword term="physical operators, constant scan"/>
			<keyword term="logical operators, constant scan"/>
		</keywords>
		<links>
			<link href="Execution Plan Reference.html">Execution Plan Reference</link>
		</links>
	</head>
	<body>
		<summary>
			<p>
				The <b>Constant Scan</b> operator introduces zero or one row into a query. A <a href="Compute Scalar.html">Compute Scalar</a>
				operator is often used to add columns to a row produced by a Constant Scan operator.
			</p>
			<p>
				The <c>Empty</c> property indicates whether this operator will introduce a row. For example, an empty
				<b>Constant Scan</b> is produced for a query for which the <c>WHERE</c> clause is always <c>FALSE</c>.
			</p>
			<p>
				<b>Constant Scan</b> is a logical and physical operator.
			</p>
		</summary>

		<section title="Properties">
			<table>
				<tr>
					<th>Property Name</th>
					<th>Description</th>
				</tr>
				<tr>
					<td>Empty</td>
					<td>
						Indicates whether this <b>Constant Scan</b> actually represents an empty table.
					</td>
				</tr>
				<tr>
					<td>Defined Values</td>
					<td>Specifies the set of values stored in the table.</td>
				</tr>
			</table>
		</section>
	</body>
</topic>
